#include?
#include?
#include?
#include?
#include?
#include?
#include?
#include?
#include?
#include?
#include?
#include?
#include?
#include?

#define?MAX_EVENT_NUMBER?1024
static?int?pipefd[2];

int?setnonblocking（?int?fd?）
{
????int?old_option?=?fcntl（?fd?F_GETFL?）;
????int?new_option?=?old_option?|?O_NONBLOCK;
????fcntl（?fd?F_SETFL?new_option?）;
????return?old_option;
}

void?addfd（?int?epollfd?int?fd?）
{
????epoll_event?event;
????event.data.fd?=?fd;
????event.events?=?EPOLLIN?|?EPOLLET;
????epoll_ctl（?epollfd?EPOLL_CTL_ADD?fd?&event?）;
????setnonblocking（?fd?）;
}

void?sig_handler（?int?sig?）
{
????int?save_errno?=?errno;
????int?msg?=?sig;
????send（?pipefd[1]?（?char*?）&msg?1?0?）;
????errno?=?save_errno;
}

void?addsig（?int?sig?）
{
????struct?sigaction?sa;
????memset（?&sa?‘\0‘?sizeof（?sa?）?）;
????sa.sa_handler?=?sig_handler;
????sa.sa_flags?|=?SA_RESTART;
????sigfillset（?&sa.sa_mask?）;
????assert（?sigaction（?sig?&sa?NULL?）?!=?-1?）;
}

int?main（?int?argc?char*?argv[]?）
{
????if（?argc?<=?2?）
????{
????????printf（?“usage:?%s?ip_address?port_number\n“?basename（?argv[0]?）?）;
????????return?1;
????}
????const?char*?ip?=?argv[1];
????int?port?=?atoi（?argv[2]?）;

????int?ret?=?0;
????struct?sockaddr_in?address;
????bzero（?&address?sizeof（?address?）?）;
????address.sin_family?=?AF_INET;
????inet_pton（?AF_INET?ip?&address.sin_addr?）;
????address.sin_port?=?htons（?port?）;

????int?listenfd?=?socket（?PF_INET?SOCK_STREAM?0?）;
????assert（?listenfd?>=?0?）;

????//int?nReuseAddr?=?1;
????//setsockopt（?listenfd?SOL_SOCKET?SO_REUSEADDR?&nReuseAddr?sizeof（?nReuseAddr?）?）;
????ret?=?bind（?listenfd?（?struct?sockaddr*?）&address?sizeof（?address?）?）;
????if（?ret?==?-1?）
????{
????????printf（?“errno?is?%d\n“?errno?）;
????????return?1;
????}
????//assert（?ret?!=?-1?）;

????ret?=?listen（?listenfd?5?）;
????assert（?ret?!=?-1?）;

????epoll_event?events[?MAX_EVENT_NUMBER?];
????int?epollfd?=?epoll_create（?5?）;
????assert（?epollfd?!=?-1?）;
????addfd（?epollfd?listenfd?）;

????ret?=?socketpair（?PF_UNIX?SOCK_STREAM?0?pipefd?）;
????assert（?ret?!=?-1?）;
????setnonblocking（?pipefd[1]?）;
????addfd（?epollfd?pipefd[0]?）;

????//?add?all?the?interesting?signals?here
????addsig（?SIGHUP?）;
????addsig（?SIGCHLD?）;
????addsig（?SIGTERM?）;
????addsig（?SIGINT?）;
????bool?stop_server?=?false;

????while（?!stop_server?）
????{
????????int?number?=?epoll_wait（?epollfd?events?MAX_EVENT_NUMBER?-1?）;
????????if?（?（?number?????????{
????????????printf（?“epoll?failure\n“?）;
????????????break;
????????}
????
????????for?（?int?i?=?0;?i?????????{
????????????int?sockfd?=?events[i].data.fd;
????????????if（?sockfd?==?listenfd?）
????????????{
????????????????struct?sockaddr_in?client_address;
????????????????socklen_t?client_addrlength?=?sizeof（?client_address?）;
????????????